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#include "lockf.h"
#include "string.h" /* for memset */
#include "unistd.h" /* for getpid */
#if !defined HAVE_LOCKF
#include <sys/types.h> /* for off_t */
#include <errno.h> /* for errno */
int lockf( int fd, int cmd, off_t len ) {
struct flock fl;
memset( (char *)&fl, 0, sizeof( fl ) );
/* lockf is always relative to the current file position. */
fl.l_whence = SEEK_CUR;
fl.l_start = 0;
fl.l_len = len;
errno = 0;
switch( cmd ) {
case F_TEST:
fl.l_type = F_RDLCK;
if( fcntl( fd, F_GETLK, &fl ) < 0 ) {
return -1;
}
if( fl.l_type == F_UNLCK ||
fl.l_pid == getpid( ) ) {
return 0;
}
errno = EACCES;
return -1;
case F_ULOCK:
fl.l_type = F_UNLCK;
cmd = F_SETLK;
break;
case F_LOCK:
fl.l_type = F_WRLCK;
cmd = F_SETLKW;
break;
case F_TLOCK:
fl.l_type = F_WRLCK;
cmd = F_SETLK;
break;
default:
errno = EINVAL;
return -1;
}
return fcntl( fd, cmd, &fl );
}
#else
extern int dummy; /* prevent ISO C forbids an empty source file' warning */
#endif /* !defined HAVE_LOCKF */
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